The present invention relates to ramp doors of the type that are pivoted along a bottom edge thereof for movement between an “up” or “closed” position wherein the ramp door closes at least a portion of an opening in an upstanding wall of a cargo compartment, and a “down” or “open” position wherein the ramp door may serve as a ramp to facilitate the movement of cargo, vehicles and/or personnel through the opening during loading and unloading of the cargo compartment.
Ramp doors typically have been large and heavy. A large size often is required, especially when a ramp door is used to close the rear of a vehicle's cargo compartment, because the width and height of the ramp door have needed to substantially equal the width and height of rear portions of the vehicle's cargo compartment. A heavyweight construction has commonly been employed to give the ramp door the capability, when serving as a ramp, to resist sagging or buckling under the weight of cargo, vehicles and/or personnel being moved into and out of the associated cargo compartment.
The heavier and more awkward a ramp door is to pivot between open and closed positions, the greater is the need for a lift system to assist with the door's pivotal movement. Although a variety of door closure assist systems employing cables, pulleys, springs and the like have been proposed, a problem commonly encountered with such systems when installed on sizable ramp doors has been the need for lengthy reaches of tensioned lift cable to be exposed to view and to unwanted contact when the ramp doors are open—lengthy exposed reaches of cable that bridge from cargo compartment walls or door frame uprights located on opposite sides of an opening (where lift assist components are housed in hollow interior portions of the walls or door frame uprights) to locations along opposite sides of a ramp door where the cables connect to the ramp door. The exposure of lengthy reaches of cable to undesired contact can result in damage and breakage not only to the cables and other closure assist system components but also to goods being loaded and unloaded through cargo compartment openings.
Although it is known to utilize cores of honeycomb material in the construction of lightweight doors for residential and commercial buildings, relatively lightweight doors of honeycomb core construction have not, until now, been found to serve acceptably as walk-on or drive-on ramps for the loading and unloading of small off-road recreational vehicles and other goods and cargo from the transport compartments of trucks, trailers and the like, especially where the cargo compartment openings to be closed by the doors are quite wide and tall, and especially wherein the doors, when open, are called on to provide relatively long walk-on or drive-on ramps.
Slam capable latches, also referred to as “slam latches,” are well known for use with vehicle closures. Many slam latches designed for use on vehicles have rotary bolts that typically are retained in latched orientations by ratchet type pawls. Patents assigned to The Eastern Company that disclose a variety of rotary-bolt slam latches include U.S. Pat. Nos. 6,543,821, 6,513,353, 6,490,895, 6,471,260, 6,454,320, 6,427,500, 5,884,948, 5,611,224, 5,595,076, 5,586,458, 5,564,295, 5,439,260, 5,192,096, 5,171,048, 5,117,665, 5,069,491, 4,917,412, 4,896,906, 4,703,961, 4,457,146, 4,320,642 and 4,312,203, referred to hereinafter as the “Slam Latch Patents,” the disclosures of which are incorporated herein by reference.
Push button actuator assemblies that are designed to move rigid links such as rods, or flexible links such as wire cables in response to depression of push button operators are well known for use in operating remotely located latches, including many of the slam latch assemblies disclosed in the referenced Slam Latch Patents. Among pending applications and issued patents assigned to The Eastern Company that disclose push button actuator assemblies designed to move rigid and flexible links such as rods and cables to operate latches in response to depression of push button operators are U.S. Pat. Nos. 6,899,362, 6,755,449, 6,543,821 and 6,454,320 and application Ser. No. 10/896,409, referred to hereinafter as the “Push Button Actuator Patents,” the disclosures of which are incorporated herein by reference.
Design patents assigned to The Eastern Company that disclose appearance features of assemblies that may be used with push button actuators to cause operation of remotely located latch assemblies include Design Patents D-474,673, D-474,098, D-472,449, D-471,427, D-467,786, D-464,555, D-463,247, D-447,042 and D-445,015, referred to hereinafter as the “Push Button Actuator Design Patents,” the disclosures of which are incorporated herein by reference.